21 of the most iconic photos ever taken. The image of a napalm scarred little girl running from her burning village in Vietnam is one of the most well known photographs in the world. Kim Phuc, the girl featured in the image, is now receiving free laser surgery to cover her scars, 40 years after that terrible day.
1 Oxygen: Specialized nerve cells within the aorta and carotid arteries called peripheral chemoreceptors monitor the oxygen concentration of the blood and feed back on the respiratory centers. 2  If the oxygen concentration in the blood decreases, they tell the respiratory centers to increase the rate and depth of breathing. This mechanism prevents damage to the lungs that would be caused by over-inflation. 2  Signals from higher brain centers: Nerve cells in the hypothalamus and cortex also influence the activity of the respiratory centers. 3  During pain or strong emotions, the hypothalamus will tell the respiratory centers to speed up.
A sympathetic nerve block can be used to diagnose and/or treat pain disorders involving the sympathetic nervous system. The injection consists of a local anesthetic. The sympathetic nervous system is a network of nerves throughout your body. The nerves branch from your spine and control some body functions, such as the closing of blood vessels. A problem with these nerves can affect blood flow and cause symptoms in the hands or feet. They may hurt, burn, feel cold, or be tender to touch. The sympathetic nervous system is controlled by bunches of nerves called ganglions. One large ganglion, called the stellate ganglion, helps control nerves in the upper body.